Heretofore, for a recording medium, such as a disc, etc., techniques for a large capacity have been variously developed. It is also demanded that recording and reproducing of various data, etc., such as, for example, audio data, data for a computer application for one medium can be realized. Regarding development of general-purpose media, compatibility and consistency of a conventional recording/reproducing apparatus, etc. are important. It is preferable as seen physically that conventional resources can be effectively utilized.
A Minidisc (MD: Registered Trademark) of one type of a magneto-optical disc which has been widely used will be described as an example. The minidisc is a magneto-optical disc having a diameter of 64 mm, which can record and reproduce audio data of music, etc. In the minidisc, audio data is recorded by being compressed to the data amount of ⅕ to 1/10 by an ATRAC system. As an example of audio data, the minidisc can record the data of the amount for about 80 to 160 min. The minidisc adopts a file system which realizes high editability, such as dividing, combining, erasing, track number moving, etc. for recording data.
There has been proposed a technique for reproducing content data such as music, video, etc. recorded in package media such as CD-DA (Compact Disc Digital Audio), DVD (Digital Versatile Disc), etc. by a personal computer (PC), and by using an HDD (Hard Disc Drive) of the PC as a primary recording medium, copying or moving the content data to the minidisc that is a secondary recording medium.
In the technique heretofore proposed, it has been realized to manage the right of the contents even if transfer data is encrypted at data transfer time between the PC and a terminal and further the content data (data as a unit of a musical song, etc., called a tracks) is edited, and to take the consistency of so called check-in (transfer of rights)/check out (return of rights) in an SDMI (Secure Digital Music Initiative) system.
Since the minidisc for audio can be easily acquired by a user, it is very convenient if this minidisc can be widely utilized other than the application of music, for data storage media, etc for a computer. However, since the recording capacity of the minidisc is small, about 160 MB, an area for recording copyright protection information of ID, etc. peculiar to media is not prepared. Therefore, on the assumption that the minidisc is used as a wide data storage for music and/or video distribution, etc., there is a problem that the minidisc cannot be dealt with a request of copyright protection, etc. of the distributed contents. Further, since the minidisc adopts a managing system (PTOC (Premastered Table Of Contents), UTOC (User Table Of Contents)) by a specific managing area except audio data recording area, it is difficult to deal, for example, with a general-purpose file system application, such as an FAT system, etc. Furthermore, if data except audio is recorded in a track under the UTOC management, a fault is generated, such as generation of abnormal noise at a reproducing time in many audio devices (MD players). That is, if it is assumed that the minidisc for audio is used as general-purpose storage media, a recording capacity, a managing system, specific information related to copyright protection, etc., faults in conventional type become problems.
As a standard for the purpose of data recording except audio data in the minidisc system, the disc standards called “MD-DATA”, or “MD-CLIP” have already been developed. However, the MD-DATA does not satisfy the above-mentioned demand, because it is a dedicated disc different from the MD for audio, usable only for dedicated recording/reproducing apparatus for the MD-DATA, has a recording capacity of about 140 MB, and so on. Further, since the MD-CLIP can use the MD for audio and utilizes an inner peripheral part out of UTOC management, there is no inconvenience in a conventional audio device, but since the general-purpose recording area is only about 2 MB, its application is limited by itself.
Therefore, there is proposed a next-generation minidisc in which the above-mentioned faults are solved by narrowing a track pitch and making improvements in changing a linear speed and a modulation method to realize a high density of recording data, and further providing a normal recording area a conceal area (secure area) usable by an authentication. These next-generation minidiscs adopt a new managing data configuration different from the UTOC, and record specific data by encrypting unlike the conventional minidisc which records a plain text. In the next-generation minidisc, data such as musical contents, video contents, etc., in which a copyright is created is recorded by a predetermined format in a secure area and the secure area can be reproduced only by a device which can be referred to. In the minidisc in which a new modulation method is adopted, since musical data of high tone quality can be recorded and reproduced for a long time, the number of musical songs to be managed by one disc becomes large. Further, this minidisc intends to take affinity with a computer by managing data by using an FAT file system.
However, in the file system such as an FAT file system, etc., when a series of musical files or video files are divided on the way of a cluster by dividing, combining, erasing, track number moving, etc., it is necessary to move the one of the divided clusters to another area. Then, continuous reproducing of the divided files becomes difficult. Further, if the musical file is, for example, reproduced from the midway of the track, it is necessary to trace the continuous information (cluster link table) of the cluster for acquiring the cluster number on the disc, and hence it has taken a much time to calculate for the reproducing process. If reverse reproducing is executed, a cluster link in reverse direction must be formed, and hence there is a problem that many memories must be consumed.